Restless legs syndrome (RLS) is very common in older subjects, particularly in Western countries such as the United States. RLS can lead to severe insomnia and subsequent daytime hypersomnia. RLS resulted in the first successful results from a genome-wide association study (GWAS) in the field of sleep disorders. Insomnia can present as a primary disorder or as a symptom of comorbid conditions such as chronic pain. Comorbid insomnia is more common in older adults, which in part is a reflection of higher prevalence of comorbid medical conditions and significant progress has been made in identifying the genetic basis of some forms of sleep disorder such as RLS and narcolepsy, the genetic basis of obstructive sleep apnea (OSA) remains to be determined. In the sleep disorders, progress has been made in understanding the etiology of narcolepsy and RLS largely through the application of genome-wide association studies to the phenotypes.